In the production and merchandising of goods, it is often desirable to make use of removable coupons, signage or labels contained on supports, containers, folders or packages that function as changeable signage such as for advertising, redeemable retail coupons, inventory control labels, and the like. In these functions, it is desirable and often necessary that the removable piece not be prone to premature detachment during exposure to the elements if signage, shipping and handling if a reusable container, premature loss if a coupon with value and yet be readily and cleanly removable.
Furthermore, inventory control labels, especially those affixed to reusable signage and containers, are subject to abrasion during shipping and handling and to chemical attack by spillage of the container contents. Abrasion and chemical attack can destroy important information on the label and result in premature detachment of the label from chemical attack and, in the case of relabeling where the release surface is a coated release surface such as a silicone coating, can increase the difficulty in removability of the label.
French Patent 2 649 522 to Raffegeau describes a coated film or paper element having a silicone coating on one side and an adhesive on the opposite side. This structure is used on reusable containers as a relabeling substrate to avoid a messy build up of adhesive when an old label is removed to be replaced with a new label.
U.S. Pat. No. 4,767,654, to Riggsbee “DETACHABLE COUPON LABEL”, describes a label structure appropriate for attaching to packages or containers which permits the coupon label to be readily detached without leaving a tacky residue and without the use of a coated release substance. Specifically, Riggsbee requires the use of London or dispersion forces to attach the coupon at a desirable release force, in the range of 10-100 g/inch width, to a base sheet without making use of either an adhesive or a coated release substance. To accomplish his objectives, Riggsbee requires that the coupon layer be the substrate for “casting” a thin extruded film of resin so as to retain detachability without damage to the substrate and without leaving a tacky residue.
U.S. Pat. No. 5,628,858 and RE37,164 to Petrou “LABEL SYSTEM FOR REUSABLE CONTAINERS AND THE LIKE”, requires the use of a multilayer laminate called a “placard” having a release coating on one side and an adhesive on the other side for securing the placard to the container. The placard may be partially transparent with instructional printing applied to one surface. Pressure-sensitive labels are placed on the exposed release-coated surface of the placard. The labels contain indicia relating to the status of the container. When the status of the container changes, the label is removed and a new label is substituted on the placard. As a preferred embodiment, the placard is provided on one face with a coated silicone release substance.
U.S. Pat. Nos. 6,986,826 and 6,667,086, to Dronzek, Jr. disclose that an extruded and subsequently laminated Teflon® film overlaminate provides a placard having a more durable release surface than the coated release surface of the Petrou placard. While this product which is based on a solid extruded film at least 0.5 mil in thickness is a major improvement over a coated release system that is subject to loss of release properties, loss of performance through abrasion and loss of coating over repeated used, Teflon along with other fluoropolymer based films having release properties are very costly and are not cost competitive with release coated packaging films such as release coated polypropylene.
U.S. Patent Publication No. 2006-0054266 to Kennedy, describes placards inserted with RFID transponders that achieves a release film surface for the removal of pressure sensitive labels by using a pliable film that forms a hermetic seal and has a release surface which may be a coating applied to a protective layer or may be a property of the material from which the protective layer is made.
Entirely different approaches to embossed surfaces have been used in the past as separation sheets for items such as rubber and other materials that could stick together as a means to promote separation. They also have been used in a limited way as release backing for pressure sensitive tapes manufactured from durable face stocks such as films and foils (not paper based) so they are strong enough to be removed without destruction as bond builds over time. In these applications, a very firm adhesive system is used. The adhesive needs to be firm because as the tape is rolled up under tension, if the adhesive is not firm, it will be forced under pressure to flow into the embossed cavity and will bond and not readily remove. Embossing a film increases the overall surface area as compared to a flat smooth surface. If the adhesive is not firm and is applied with pressure, such as in a wound roll or stack, in many cases it will actually develop a stronger bond over time because of penetration into the embossed area than the same adhesive would on a smooth surface of the same material.
Entirely different approaches to embossed polymeric substrates have been used in a limited way in the label arts as release backings in combination with durable polymeric substrate face stocks as in the tape arts also with very firm adhesives. These adhesives are typically classified as removable because they remove cleanly from many surfaces and are much more costly than typical adhesive systems used on paper labels. Because they are firm, they do not readily flow into the embossed cavity, but if they do the durable polymeric face stock can still be separated without destruction.
Entirely different approaches to films with embossed surfaces have been used as liners having a release surface in combination with adhesive film products having high tensile strengths. These high tensile strength products will resist tearing and deformation when they are separated from the textured or embossed film surface. However, in the prior art, textured or embossed films have not been used as release liners for paper labels because of the tendency of paper labels, due to the low tensile strength of paper, to tear when removed from a film surface that does not have a release coating or has not been made from a material with inherent release characteristics like fluoropolymers. This occurs after they have been in place for a prolonged period of time where the adhesive has had a chance to build, particularly under adverse conditions such as pressure from being wound in a roll or when placed under a force such as a stack of labels and subjected to temperature, causing the adhesive to soften and flow under pressure or load.